Electrical contact-making keyboards

ABSTRACT

A series of laterally spaced brackets are secured together by a printed circuit board on which is mounted a parallel array of Lshaped wires having their short legs molded in a plastic block and their long legs disposed in slots in a plastic guide member. Plastic keys are pivoted at one end to a bar supported by the brackets, and have plugs at an intermediate position which are guided into predetermined slots in the guide member when the keys are depressed. Key circuits are molded into each key and, upon contact of the plug with the long leg of an L-shaped wire in the selected slot, connect two binary bit wires constituting the binary code of the depressed key to a binary code terminal strip.

ELECTRICAL CONTACT-MAKING KEYBOARDS Inventors: Haydn V. Purdy, Down Cottage, Down Place, Windsor; Ronald C. McIntosh, 7 Avenue Road, St Albans, both of England Filed: Aug. 10, 1970 Appl. No.: 62,530

US. Cl. ..340/365, 200/5 E, 317/101 B Int. Cl ..G08c 9/08 Field of Search .340/365; 178/17 C, 17 A;

References Cited UNITED STATES PATENTS Dinsmore "340/365 Wright ..,....340/365 [451 June 6, 1972 OTHER PUBLICATIONS Primary Examiner-Thomas B. Habecker Attorney-Marechal, Biebel, French & Bugg [57] ABSTRACT A series of laterally spaced brackets are secured together by a printed circuit board on which is mounted a parallel array of L-shaped wires having their short legs molded in a plastic block and their long legs disposed in slots in a plastic guide member. Plastic keys are pivoted at one end to a bar supported by the brackets, and have plugs at an intermediate position which are guided into predetermined slots in the guide member when the keys are depressed. Key circuits are molded into each key and, upon contact of the plug with the long leg of an L-shaped wire in the selected slot, connect two binary bit wires constituting the binary code of the depressed key to a binary code terminal strip.

9 Claims, 3 DrawingFigures PATENTEDJuN smz 3,668,694

SHEET 1 OF 2 FIG.

FIG.

INVENTORS HAYDN V. PURDY & RONALD C. McINTOSH ATTORNEYS PATENTED JUN 6 I972 3, 668 694 sum 2 OF 2 INVENTORS HAYDN V. PURDY 8:

RONALD C. MclNTOSH ATTORNEYS ELECTRICAL CONTACT-MAKING KEYBOARDS This invention relates to electrical contact-making keyboards and has for its object an economical yet reliable keyboard.

The main aspect of the invention comprises an electrical contact-making keyboard wherein the keys are pivoted on a common rod without lateral restraint and lateral guidance means are provided at an intermediate position along the keys.

This invention will be clearly understood from the following description of a preferred embodiment shown in the accompanying drawings, in which:

FIG. 1 is a schematic side elevation of the essential parts of the keyboard FIG. 2 is a perspective view of the electrical contact-making elements associated with a single key, while FIG. 3 shows the basic electrical circuit diagram of the keyboard.

Keyboards for the generation of coded signals at present commonly employ rigid mechanical assemblies of metal parts and have to contend with sometimes conflicting requirements such as ergonomic aspects of key disposition and operation relevant to human efficiency and accuracy, contrasted with the desiderata of mechanical and electrical characteristics for reliability and long life.

In the keyboard hereinafter described these design considerations, and the compromises they imply, are the basis of an economical integration of mechanical and electrical features.

The keyboard is so designed that the positional controls for the parts are minimized so that as may parts as possible can be manufactured with easy tolerances, and can be easily assembled and dismantled. In particular the keys 1 (FIG. 2) can be moulded in plastics material and can be assembled and dismantled without the use of tools; their pivot collars 2 having bores 3 with entrance slots 4 to allow the keys 1 to be slipped on and off a plain pivot rod 9 common to all the keys. The pivot rod 9 can be cylindrical being forced through the undersize slot 4 due to the elasticity of the plastics material; or can be flattened along a surface to allow the keys to be slipped in in an angular position outside their operational angle of swing. Many other parts can also be moulded in plastics material. I

Complementary sets of keys otherwise identical, have their individual key-top supports; e.g. 81 84; at different locations along the key length to form a conventional keyboard array. Detachable or integral key tops on the supports are engraved with respective characters.

One end of an elastic electrical conductor wire (or strip) 5; which is to act as a key-return spring; one end of an electrically conductive plug 6; and a conductor 7 electrically connecting the wire 5 and the plug 6, are moulded in each key for completing an electric signalling circuit in the manner to be described when a mounted key is depressed. The end of plug 6 is preferably wholly within the thickness of the key, and the spring wire or strip 5 is preferably predistorted within the key body to prevent twisting of its free portion, and its gauge and its angle relative to the axis of the key are chosen to provide the resistance to key depression and the key return force required by the desired ergonomic requirements.

It will be understood that the keyboard will consist of a lateral succession of sets of keys, each set comprising closely spaced keys with tops 81 84 in turn, so that successive keys with similarly positioned tops: e.g. 81, 81; are separated by three intervening keys so as to be at approximately finger distance apart and the whole is a close approximation to a conventional typewriter keyboard.

Such an assembly consists of keys 1 freely pivoted on the common bar 9 passing freely through the succession of bores 3. The common bar 9 is in turn supported at regular intervals; e.g. after every sixteenth key; by key brackets 11, also bored and slotted to receive the bar 9 in the same way as the keys. The brackets 11 have feet 12, 13 adapted to be bolted to base runners and top lugs 14 for bolting to top spacing members. At

least one end of bar 9 is a close fit in the bore of the respective end bracket in which the bar is fixed by a fixing pin passing through diametrical pinholes in the bracket and in the bar 9.

Each bracket is apertured at 15 and the lower edge of the aperture carries vertical pegs l6 spaced to receive a spring tensioning bar 17 which can be inserted in any slot between aligned adjacent pairs of pegs in all the brackets. The tensioning bar 17 has a row of lateral slots the pitch of which is the same as the pitch of the keys 1 and which are positioned to receive the free ends of the spring wires 5 so as to tension them as shown, to the required degree, which can be varied by inserting bar 17 in different interpeg slots.

The tensioning bar is made of electrically conductive material and forms a common terminal for the key circuits 6, 7,5.

An electrical multi-bit binary code generating equipment operable by the keys is supported below the keys on rows of platforms 18,19 on the brackets 11 in position for operation by the plugs 6 forming the selective terminals of the individual electrical key circuits which pass from the common terminal bar 17 through the individual spring wires 5 and internal conductors 7 to the plugs 6.

Basically the generating equipment consists of I. a two-sided printed circuit board comprising on one side sixteen parallel bit wires for generating 2 out of 16 binary codes, and on the other side at right angles to the bit wires, pairs of wires, one pair per key, with connections through the board, at suitable locations, between each individual wire of the 64 pairs of wires, one pair per key, to a respective bit wire.

II. means for making connection between any one of the key plugs 6 and the corresponding pair of key wires on the printed circuit board. The spacing of the pairs of key wires is identical with the spacings of the keys on the keyboard.

The means II is arranged to provide precise and accurate interconnection despite the wide manufacturing and assembly tolerances elsewhere in the construction, and comprises a. a parallel array of 2 X 64 L-shaped spring wires mounted on the circuit board and having one set of ends permanently connected to the respective printed key wires on the printed circuit board and the other set of ends positioned for contact by the respective key plugs when depressed; and

b. integral guides for both the wire ends and the plugs which ensure correct contact therebetween.

The printed circuit board 20, FIG. 1 is drilled with locating holes for mounting on the platforms 18, 19 with the key wiring underneath and parallel to the keys.

vThe spring wire array; Ila above; is shown in FIG. 3 and consists of a rectangular plastics strip 21 within which the angles of the L-shaped wires are molded so that their short legs 22 emerge in parallel from the base of the strip and the long legs 23 extend from one edge of the strip.

The integral guide member 30; II (b) above; is shown in FIG. 2 and is a plastics moulding comprising three sets of partitions parallel both within and between the sets, all integral with a member 24 of L cross-section, one leg of which is a solid bar.

Two of the sets of partitions are related to the contact-making problem; a set 25 in the angle of the member 24, the partitions providing an individual slot for each of the long legs 23 of the spring wire array; and a set 26 on, and extending beyond the outer ends of the long outer face of the member 24, the partitions being spaced so as to form slots having a width to receive the plugs 6 of the keys which are wide enough to overlap the long legs 23 of the respective pair of spring wires extending below the slots 28.

The third set of partitions 29 are dog-legged extensions 31,32,33 of the set 26 which are partly carried by the member 24, and are for a purpose to be described later.

The plastics strip 21 of the spring wire array and the guide member 30 are also drilled with locating holes for alignment respectively with locating holes at the rear and front ends; with respect to the keyboard; of the printed circuit board 20. The spring wire array 21 23 and the guide member 30 are mounted with the printed circuit board on the platforms l8, 19 in relative position such that the outer ends of the long legs 23 of the spring wires are entered in the slots in the partition set 25; and press against the roofs of the slots.

On depression of a key, its plug 6 will enter into the respective slot and will be guided to contact the pair of spring wires 23 in the individual pair of slots immediately below.

Thus, correct contact is assured, and binary code circuits are set up from the earthed tensioning bar 17; through the key circuit 5,7,6; the respective pair of spring wires 23,22; through the circuit board 20, along the two printed key wires on the underside of board 20; back through the board to the two binary bit wires constituting the binary code of the depressed key, and thence to the binary code terminal strip.

It is significant that the printed circuit board serves a mechanical purpose in that when appropriately attached to all the brackets 11 it makes the whole into a rigid assembly.

The slotted guide member has amongst its functions, as stated above, that of guiding each metal plug 6 accurately over the two associated spring contacts 23, appropriate to its code. This is made practical by having the two apertures which constrain each pair of spring contacts closer together than the width of the plug 6.

The third set of guide slots between partitions 29 receive the ends of the keys. The partitions 29 have horizontal end sections 33 of a predetermined flexure, the purpose of which is to mate with transverse projections 34 on the key ends and so prevent the keys from leavingthe guide slots under the influence of their return springs 5. The flexure and thickness,

however, do permit a key to be pulled out of the guide slot provided a suitable additional force is applied. In conjunction with the slotted hinge at the back of the key, this enables any individual key to be inserted into or removed from the assembly, without disturbance to its'neighbors.

To provide additional parallelism over the area of the symbol-bearing keytops, or in other words to allow possible distortions in the keys to the absorbed by their permitted non-parallelism at the hinge end, a vertical separating comb of plastics material can be provided midway along the upper part of the keys, the slot pitch of this comb being equal to the slot pitch of the slotted guide already described. The thickness of the keys must be less than their pitch, thus allowing for distortion in the moulding process and room for insertion of the separating comb. The common hinge bar, supporting the keys, provides similar hingeing support for arms at each end of the plastic comb, so that the latter maybe raised to permit insertion or withdrawal of individual keys as described above.

A space bar is required at the front of the keybank, at a lower level than the front row of keys. This may be provided by employing two normal keys, only one of which has a contact and lock-out facility, separated by any convenient distance. These keys are coupled at each end by a rigid bridge so that movement of the bridge is transmitted to the contactbearing key, the suitably engraved plastic space bar itself being attached in convenient manner to the bridge furthest from the hinge. Alternatively a rigid lightweight frame having a slotted hinge at its rear corners similar to the construction of the key, may be substituted for the two connected keys described above (depression of its front edge at any point being arranged to depress a single key generating the appropriate space code).

If two keys are used in connection with a space bar, the noncontact bearing keymust have a cut-out where it crosses the slotted guide, so as not to press upon the lock-out tape, now to be described. 7

Another function of the slotted guide member 20 is to constrain a flexible, low-friction tape, or tapes, rigidly supported at either end outside the array of keys and passing across the top of the third set of partitions 29 and below each key. There is sufficient tape available to permit only one key at a time to be fully inserted between the vertical partitions 29 of the slotted guide member 20 and therefore only one key at a time is permitted to make contact with its appropriate contact springs. All other keys are prevented from entering their slots since the tape has been made taut the single depressed key.

What we claim is:

1. In an electrical-contact-making keyboard including keys pivoted on a common rod and lateral guidance means for the keys at an intermediate position along the keys, the improvement comprising,

a. means for creating any one of a plurality of operational selections in response to the depression of any one of a plurality of operational keys,

b. 'a coordinate printed circuit wired into said means tomake any one of a number of 2 out of x preset binary selections by making connection to a respective pair of contacts in the printed circuits to activate the corresponding x connections, c. at least two electrical terminals on each operation key,

and an electrical connection between said two terminals, one of said terminals being a bridging electrical contact for said respective pair of contacts in said printed circuit, the other of said terminals being in contact with a common electrical terminal for activating said printed circuit upon connection thereto. 2. A keyboard as defined in claim 1, further characterized by,

a. a key-return spring carried by the key and connected to said other terminal of said electrical connection, and

. a common return spring locating member which acts as an electrical contact and which is connected to said keyreturn spring.

3. A keyboard as defined in claim 1 comprising an array of parallel brackets each carrying platforms to which said printed circuit is rigidly affixed, the rear ends of said brackets being apertured to receive the common key rod.

4. A keyboard as defined in claim 3 wherein the key rod has a longitudinal flat thereon and said brackets and keys are formed with key-slots to receive the key rod.

5. A keyboard as defined in claim 3 wherein all nonelectrical parts are moulded in plastics material.

6. A keyboard as defined in claim 1, further characterized by, a position-control comb device arranged to guide said bridging electrical contacts into correct contact with said respective pairs of contacts in the printed circuits and to control both the lateral and vertical freedom of movement of the individual keys, said printed circuits extending below the whole row of keys and carrying said position-control comb device.

7. A keyboard as defined in claim 1, further characterized by, a base for the keyboard, said printed circuit being mounted above the base, pairs of L-shaped wire terminals on the upper face of said printed circuit, the long legs of which are parallel to said base and are positioned to cooperate with respective bridging electrical contacts on the keys, and a linear array of multibit binary code wires on the lower face of said circuit board and at right angles to said L-shaped wire terminals, to which code connections are made through the printed circuit from said wire terminals.

8. A keyboard as defined in claim 1 further characterized by, a plastics contact comb incorporating said printed circuit contacts, and a plastics slotted guide constraining both the lateral and vertical movements of the keys.

9. A keyboard as defined in claim 2 wherein said keys are moulded from plastics material and each key has molded therein the fixed end of its return spring, the base of its bridging electrical contact, and an electrical connection therebetween. 

1. In an electrical-contact-making keyboard including keys pivoted on a common rod and lateral guidance means for the keys at an intermediate position along the keys, the improvement comprising, a. means for creating any one of a plurality of operational selections in response to the depression of any one of a plurality of operational keys, b. a coordinate printed circuit wired into said means to make any one of a number of 2 out of x preset binary selections by making connection to a respective pair of contacts in the printed circuits to activate the corresponding x connections, c. at least two electrical terminals on each operation key, and d. an electrical connection between said two terminals, one of said terminals being a bridging electrical contact for said respective pair of contacts in said printed circuit, the other of said terminals being in contact with a common electrical terminal for activating said printed circuit upon connection thereto.
 2. A keyboard as defined in claim 1, further characterized by, a. a key-return spring carried by the key and connected to said other terminal of said electrical connection, and b. a common return spring locating member which acts as an electrical contact and which is connected to said key-return spring.
 3. A keyboard as defined in claim 1 comprising an array of parallel brackets each carrying platforms to which said printed circuit is rigidly affixed, the rear ends of said brackets being apertured to receive the common key rod.
 4. A keyboard as defined in claim 3 wherein the key rod has a longitudinal flat thereon and said brackets and keys are formed with key-slots to receive the key rod.
 5. A keyboard as defined in claim 3 wherein all nonelectrical parts are moulded in plastics material.
 6. A keyboard as defined in claim 1, further characterized by, a position-control comb device arranged to gUide said bridging electrical contacts into correct contact with said respective pairs of contacts in the printed circuits and to control both the lateral and vertical freedom of movement of the individual keys, said printed circuits extending below the whole row of keys and carrying said position-control comb device.
 7. A keyboard as defined in claim 1, further characterized by, a base for the keyboard, said printed circuit being mounted above the base, pairs of L-shaped wire terminals on the upper face of said printed circuit, the long legs of which are parallel to said base and are positioned to cooperate with respective bridging electrical contacts on the keys, and a linear array of multibit binary code wires on the lower face of said circuit board and at right angles to said L-shaped wire terminals, to which code connections are made through the printed circuit from said wire terminals.
 8. A keyboard as defined in claim 1 further characterized by, a plastics contact comb incorporating said printed circuit contacts, and a plastics slotted guide constraining both the lateral and vertical movements of the keys.
 9. A keyboard as defined in claim 2 wherein said keys are moulded from plastics material and each key has molded therein the fixed end of its return spring, the base of its bridging electrical contact, and an electrical connection therebetween. 